Bug 1036036 - Stop leaking docshells in Session Store tests. r=ttaubert, a=test-only
When adding a SHistoryListener in the Session Store test frame script
we were creating an intermediate global variable that was rooting the
docshell. This prevented things from being GC'd properly.
I've removed this intermediate variable and we should no longer keep
the docshell alive. This will probably also fix Bug 1036031.